the number as integer or 0 on invalid numbers.
assert(fromRoman("I") == 1); assert(fromRoman("III") == 3); assert(fromRoman("IV") == 4); assert(fromRoman("V") == 5); assert(fromRoman("XLI") == 41); assert(fromRoman("MM") == 2000); // invalids assert(fromRoman("A") == 0);
Converts a roman number to an integer.